MEMS Microphone Package Notch Mounting for Low Profile
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Solution Overview
Problem
Conventional MEMS microphones have a large package size and low sensitivity due to the use of wire bonding, which is inconsistent with the trend towards low profile packaging and occupies space in the chamber, minimizing the back volume and thus reducing sensitivity.
Innovation Solution
A MEMS microphone package design featuring a substrate with a sound hole and notch, where the processor chip is mounted in the notch without occupying chamber space, allowing for wire bonding connections and a larger back volume, and a cover plate with solder pads for electrical connections, enabling a low-profile and high-sensitivity configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonding technology is used to electrically connect the acoustic wave sensor and ASIC to the substrate, then reliable electrical connection is achieved, but the package height increases and the chamber space is reduced
Solution Approach 1:
The patent transitions from vertical wire bonding (occupying height dimension) to planar trace routing (utilizing surface area dimension). The conductive traces are formed on the substrate surface to electrically connect the acoustic wave sensor and ASIC, eliminating the need for vertical metal wires and reducing package height while maintaining electrical connectivity.
Solution Approach 2:
The patent extracts the electrical connection function from the vertical wire bonding structure and relocates it to the substrate plane. By removing the metal wires that extend vertically from the substrate, the design eliminates the height requirement while preserving the essential electrical connection functionality through substrate-integrated traces.
2Reliability
If the acoustic wave sensor and ASIC are disposed in the chamber surrounded by the cover plate and sidewall, then complete packaging is achieved, but the back volume is minimized and sensitivity is reduced
Solution Approach 1:
The patent relocates the processor chip from the vertical Z-axis (chamber space) to the horizontal XY-plane (substrate surface notch). This dimensional transition allows the chamber to be optimized for acoustic performance with adequate back volume, while the processor chip occupies substrate surface area that would otherwise be unused, achieving both complete packaging and enhanced sensitivity.
3Reliability
If the sidewall is designed to accommodate metal wires for wire bonding, then electrical connection is enabled, but the profile height increases
Solution Approach 1:
The patent removes the requirement for the sidewall to accommodate vertical metal wires by extracting the electrical connection function to the substrate plane. The sidewall can now be minimized in height since it only needs to provide lateral enclosure, while electrical connectivity is achieved through substrate traces that do not require vertical clearance.
Data Source
AI summary
A MEMS microphone package includes a substrate including a base layer, a sound hole cut through opposing top and bottom surfaces of the base layer, a conduction part arranged on the base layer and a notch located on the top surface of the base layer, a sidewall connected with one end thereof to the top surface of the base layer and having a conducting line electrically connected to the conduction part, a cover plate connected to an opposite end of the sidewall and having a solder pad and a third contact disposed in conduction with the solder pad and electrically connected to the conducting line, a processor chip mounted in the notch and electrically connected to the conduction part, and an acoustic wave sensor mounted on the base layer to face toward the sound hole and electrically connected to the processor chip.